Elements on canvas not showing for an user


I have some app I use with some friends, everything works fine for all of them but one have a strange issue.
This is an app that is only showing graphic elements on a canvas. When he’s asked for a login he see the interface just fine. They are manually set with GUI.Button or GUI.Label functions. After that the Unity canvas should be displayed but he only see the empty skybox behind.

He runs it on a vista x86 and seems to have some issue with his computer recently. It worked fine 3 months ago.

Any idea of what is going on?

It is difficult to troubleshoot this issue without any code. But my guess would be , it might be the resolution. The buttons and the label must be rendered but they must be configured for lower resolution or something. Also, are you using the OnGUI() method to draw all your GUI.Button and GUI.Label functions ?

My friend just tried with the old version of my program (which doesn’t change much by the way) which was built with an older version of unity (5.2.2f1) and it worked.
Not really a fix but better than nothing.
Now that really sounds like a Unity update problem (I’m using 5.4.1f1 btw) combined with a specific combination of circunstances.